import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
                Scanner in = new Scanner(System.in);
                int[] grade = new int[5];
                for(int i=0; i<grade.length; i++){
                      grade[i] = in.nextInt();
                 }       
                for(int i=0;i<grade.length;i++){
                  for(int j=i;j<grade.length;j++){
                    if(grade[i]<grade[j]){
                      int a=grade[i];
                      grade[i]=grade[j];
                      grade[j]=a;
                    }
                  }
                }
                RR rr = new RT(grade);
                double dd = rr.mark();
                System.out.printf("%.2f",dd);
    }
}
abstract class RR{
   int[] grade;
   public RR(int[] grade){
      this.grade = grade;
   }
   public abstract double mark();
}
class RT extends RR{
  RT(int[] grade){
        super(grade);
  }
  public double mark(){
    double z;
    z=(grade[1]+grade[2]+grade[3])/3;
    return z;
  }
}
